This invention is in the field of semiconductor infrared detectors. In particular, it is concerned with multilayered epitaxially-grown devices in which one layer is a low band-gap semiconductor such as HgCdTe and another layer is a wider band-gap semiconductor such as ZnCdTe. Various growth techniques have proven successful in the preparation of single layer devices. These include liquid phase epitaxy, vapor phase epitaxy, close-spaced vapor phase epitaxy, organo-metallic vapor phase epitaxy and molecular beam epitaxy. None of these has been successfully used to provide multilayered structures. All but molecular beam epitaxy must be performed at substrate temperatures too high to allow high quality junction formation between the various layers. The molecular beam epitaxy technique is, in principle, capable of producing all layers of a structure but the technology of growth for HgCdTe, a prime constituent of the structure, is not yet mature. The instant invention capitalizes on the maturity of the other techniques, avoids their drawbacks, and capitalizes on the low-temperature characteristic of molecular beam epitaxy.